This invention relates to improvements in self-contained signal generating and transmitting apparatus. A particular example of such apparatus is a radio operated fire alarm box suitable for generating and transmitting an alarm signal to be received by a central location.
For various reasons it is often desirable to have a municipal or other fire alarm system which employs radio operated call boxes rather than units which depend upon telephone or other lines to connect the remote boxes to a central receiving station. The actual design and construction of such units, however, has posed various problems which have resulted in a minimal acceptance of such units. Such problems include the requirement of frequent visits for replacement or recharging of batteries in battery-powered units; the inability to remotely and automatically determine the continuing operability of the unit when powered from stored energy other than a storage battery; the short life time of energy sources employed in self-contained units; etc.